零拷贝示例程序

左手的ㄟ右手 2022-09-03 03:27 297阅读 0赞

示例程序实现 客户端程序将本地文件经网络IO发送至服务端。

客户端程序

package com.tech.netty.zerocopy;
    
    import java.io.FileInputStream;
    import java.io.IOException;
    import java.net.InetSocketAddress;
    import java.nio.ByteBuffer;
    import java.nio.channels.FileChannel;
    import java.nio.channels.SocketChannel;
    
    /**
     * @author lw
     * @since 2021/8/5
     **/
    public class NIOClient {
        public static void main(String[] args) throws IOException {
            SocketChannel socketChannel = SocketChannel.open();
            socketChannel.connect(new InetSocketAddress("127.0.0.1",6667));
            String fileName="1.txt";
            FileChannel fileChannel = new FileInputStream(fileName).getChannel();
            long start=System.currentTimeMillis();
            //在linux操作系统下 transferTo 传输大文件 调用一次即可
            //在windows操作系统下 transferTo 一次最多传输8M 如果文件大于8M 需要分批次多次调用传输
            //transferTo 底层使用了零拷贝技术
            long l = fileChannel.transferTo(0, fileChannel.size(), socketChannel);
            System.out.println("发送的总字节数："+l+" 耗时："+(System.currentTimeMillis()-start));
            fileChannel.close();
        }
    }

服务端程序

package com.tech.netty.zerocopy;
    
    import java.io.IOException;
    import java.net.InetSocketAddress;
    import java.net.ServerSocket;
    import java.nio.ByteBuffer;
    import java.nio.channels.ServerSocketChannel;
    import java.nio.channels.SocketChannel;
    
    /**
     * @author lw
     * @since 2021/8/5
     **/
    public class NIOServer {
        public static void main(String[] args) throws IOException {
            InetSocketAddress inetSocketAddress = new InetSocketAddress(6667);
            ServerSocketChannel serverSocketChannel = ServerSocketChannel.open();
            ServerSocket serverSocket = serverSocketChannel.socket();
            serverSocket.bind(inetSocketAddress);
            ByteBuffer byteBuffer = ByteBuffer.allocate(4096);
    
            while (true){
                SocketChannel socketChannel = serverSocketChannel.accept();
                System.out.println("客户端已连接："+socketChannel.getRemoteAddress());
                int readCount=0;
                while(-1!=readCount){
                    try {
                        readCount=socketChannel.read(byteBuffer);
                        System.out.println("读取字节数："+readCount);
                    } catch (IOException e) {
                        break;
                    }finally {
                        //倒带 position = 0 mark作废
                        byteBuffer.rewind();
                    }
                }
            }
        }
    }